BT Help

[MS3KO]

Whats up guys, so I finally got around to finishing up my turbo build. But im running into an issue. When i go to start up the car it revs to about 2k but then just dies immediately, even when i throttle the gas it revs a little bit but then dies. I checked all my lines and everything is hooked up nice and tight to my knowledge. Right now im still on a stage 2 base map, so i was thinking the tune might be the issue but im not 100% sure. Any help is appreciated. All mods are in my sig. Thanks in advance!

[XLT_66]

Have you done any work to your MAF scaling since you increased it to 3.5"?

[MS3KO]

Nahh I haven, I really didnt mess with anything involving the tune since im not very knowledgable about it.

[doubleflusher]

You need to scale you MAF or your car wont run.

Contact one of the good tuners on here.

[MS3KO]

Originally Posted by doubleflusher You need to scale you MAF or your car wont run. Contact one of the good tuners on here.

Sweet deal man thanks, ive been on the waiting list for a perm tune for months now im just gonna contact dustin and see what he says

[psychophyr]

@Lex!! Get in here and whip this dude into shape!

[atvfreek]

If you have a 3.5" maf housing multiply your maf curve by 1.3074

Highlight the maf values>enter "m" > then 1.3074 across the whole maf cal. That should get you in the ballpark

You have to do this on both maf table a and b

[86AmishMs3]

Originally Posted by atvfreek If you have a 3.5" maf housing multiply your maf curve by 1.3074 Highlight the maf values>enter "m" > then 1.3074 across the whole maf cal. That should get you in the ballpark You have to do this on both maf table a and b

this is too small. A 3.5" maf housing, probably has a .125" thick wall giving an ID of 3.25". Stock ID is like a 2.62" iirc. (3.25/2.62)^2 = 1.54. Scale by that much and that should get you close

[bmylez]

1.3074? Interesting. I have cp-e big MAF and I started off with 1.6. It was pretty damn close.

[atvfreek]

Originally Posted by bmylez 1.3074? Interesting. I have cp-e big MAF and I started off with 1.6. It was pretty damn close.

Hmmm, I simply did the math for 3.5"(88.7mm) divided by 68mm which is what most aftermarket maf housings are.

Tappin

[86AmishMs3]

Originally Posted by atvfreek Hmmm, I simply did the math for 3.5"(88.7mm) divided by 68mm which is what most aftermarket maf housings are. Tappin

Cross sectional area of a circle = pi*r^2. To get the scaling take fraction of the two.

To OP


CA1= pi*r1^2
CA2= pi*r2^2
r=d/2

Scaling factor = CA2/CA1 = (d2/d1)^2 pi cancels out and just becomes a squared ratio of the internal diameters.

[bmylez]

Yes, you get 1.54 when you compare their surface areas, however, the MAF sensor is now sitting even farther away from the center of the pipe. This means you need to add a little extra to compensate for that. Like I said, 1.6 (which was recommended by aaronc7, btw) was a very good starting point. I think my idle trims were like +6.

[atvfreek]

Originally Posted by bmylez Yes, you get 1.54 when you compare their surface areas, however, the MAF sensor is now sitting even farther away from the center of the pipe. This means you need to add a little extra to compensate for that. Like I said, 1.6 (which was recommended by aaronc7, btw) was a very good starting point. I think my idle trims were like +6.

That's good to know.

Sorry if I gave the incorrect data, I used the help file spreadsheet, and just rechecked it in there again, which still gives the incorrect #.

Although I used that spreadsheet for a 3.25" intake a while back, and it didn't seem that far off. And got me within 7%.

[bmylez]

The help sheet is *wrong*. They use the area for a circle, not the surface area for a sphere. So all they do is compute the ratio of the radii.

[MS3KO]

So dj hooked up with a base tune for my 3.5 intake and the car is running! Its rough but thats what i expected. More updates and pic coming soon!

[dooderek]

let me see a pic of your intake bro, majority of people can cal your maf, if the how to looks too crazy.

[MS3KO]

Originally Posted by Derigo let me see a pic of your intake bro, majority of people can cal your maf, if the how to looks too crazy.

Truee no doubt man im gonna take some pics soon and post them up.